Should I use a New Forest or New Tree in Existing Forest over 10mbps wireless connection?

Greetings all. I have a client who at there main site have 1 windows server 2003 server with exchange 2003 which is the root forest domain. At the remote site connected via fiber exists another server that was configured as a new tree in an existing forest for a non-contiguous name space that used the exchange at main site for mailboxes and symantec endpoint antivirus. Now we are added another server at another remote site which needs exchange access but this site will be connected via a 10mbps point-to-point wireless connection which we pre-existing. My question is, due to replication between domains in the same forest should I make this new it's own forest due to slow point-to-point connection and data replication? If I do a new forest I would obviously have to create a trust between the two forests but this would elevate speed concerns correct?

There is no reason to implement a new forest. Even if replication is slow, that doesn't mean it doesn't work. You can even schedule replication to take place in quiet hours. Processing Logons over a slow link is much more disruptive! (in case of a Trust you do get login traffic over the WAN link).
Configuring and maintaining two forests with a trust is also a LOT of work! AND you'd need to implement 2 Exchange organizations (one for each forest) which would be a nightmare especially if users on both sites use the same e-mail domain name.

Since you have Exchange server and it's for the same company, you better keep them in the same forest. As Redwulf said, creating another forest just going to create more works and complicating your AD design.